Wow, this post is hitting home. I went through exactly what you are going through .
The main reason I divorced my ex was for the same reasons. Lazy, played video games, depression, unmotivated. I always had to take care of things. I couldn't handle it.
I went back and forth with my decision. Lots and lots of drama and forgiving and trying to make things work and stuff that I won't even post here, but mark my word I have been there where you are right now.
What happened through all of it is that even when I wanted to make things work (we have a daughter together also who was 9 when I left for good), I lost my faith in him. And when you lose your faith in someone, lose your trust that they will hold up their end of the bargain, well it just puts a huge fatal blow on the love and foundation between you. I fell out of love.
The sad part is that I still cared for his well being. I left, just as you are getting ready to do, and although it was the right thing to do, I literally felt and still to this day feel sorry for him. I was his whole world, emotionally and I was the rock to keep him together. It was exhausting
So the end result is I moved on and divoced him. We are still friends for the sake of our daughter. And guess what? He is exactly the same! He still struggles every day. Still plays video games, still depressed, still lazy.
But like my fiance tells me, at least I am not in it with my ex anymore, being pulled down by him.
So I can't really tell what is "right". I only know for me I am gald I got out. But I still have a heart and feel badly for my ex. On the bright side...my daughter flourishes now because there is no money stress and fighting over unpaid bills, repossesions etc that used to make the household a stressful place when I was married. Plus I met an amazing man who is soooo responsible and caring and honest and motivated..and I love him!!
Good luck... and make your decisions based on what your heart is telling you, and what is best for your daughter.